Solar heat exchanger

ABSTRACT

A solar heat exchanger assists an air-to-air heat pump by introducing warm solar solution into thermal contact with the saturated vapor, thereby enabling the refrigerant to extract more heat at low ambient temperatures. Thus, the air-to-air heat pump is able to achieve improved heating ability at lower temperatures. The solar heat exchanger may run simultaneously and in parallel with the heat pump to thereby improve the efficiency of the heat pump.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates generally to systems for the collection, storage and transfer of heat energy and, more particularly, to heat pump systems.

SUMMARY OF THE INVENTION

The present invention is directed to a solar heat exchanger for assisting an air-to-air heat pump system. An air-to-air heat pump loses its ability to produce heat when the ambient temperature is low. The solar heat exchanger of the invention enables warm solar solution to be introduced into thermal contact with the saturated vapor. This may allow the refrigerant to extract more heat at low ambient temperatures, so an air-to-air heat pump will be able to produce its designed heating ability at lower temperatures. The solar heat exchanger may run simultaneously and in parallel with the heat pump to thereby improve the efficiency of the heat pump.

In an air-to-air heat pump system, when the ambient temperature is low, the system does not extract or produce the amount of heat that the system is capable of. Thus, in cold weather there may need to be backup heat, such as electric strip heat, or else the heat pump is locked out and the furnace is turned on. The present invention may introduce solar warmed water into the air-to-air heat pump. A heat exchanger is provided which may be thought of as a tube within a tube. The refrigerant may flow through the inside of the internal tube, and the warm solar water may flow through the external tube. Thus, the invention may introduce the warmed solar water into thermal contact with the refrigerant which has not reached full potential with regard to the amount of heat the refrigerant can extract from the air. The warm water may introduce heat into the refrigerant, and the heat may then be transferred to a condenser coil inside a building in which the heat pump is installed. Inside the building, the heat is introduced into the air and raises the air temperature within the building.

An advantage of the invention is that it enables a heat pump to heat a building adequately at low outside temperatures.

Another advantage is that the invention may use the free heat provided by solar panels to increase the efficiency of a heat pump.

BRIEF DESCRIPTION OF THE DRAWINGS

The above-mentioned and other features and advantages of the invention will become more apparent to one with skill in the art upon examination of the following figures and detailed description. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. Moreover, in the figures, like reference numerals designate corresponding parts throughout the different views.

FIG. 1 is a block diagram of one embodiment of an air-to-air heat pump system of the present invention including a solar heat exchanger.

FIG. 2 a is a diagram of the heat exchanger of FIG. 1.

FIG. 2 b is a partially sectional diagram of the heat exchanger of FIG. 1.

FIG. 3 is a block diagram of another embodiment of an air-to-air heat pump system of the present invention including a solar heat exchanger.

FIG. 4 is a block diagram of one embodiment of a forced air system of the present invention including a solar heat exchanger.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

Referring to FIG. 1, there is shown one embodiment of the air-to-air heat pump system 10 of the present invention. System 10 includes an indoor coil 12 and an outdoor coil 14. Refrigerant circulates, as indicated by arrows 16 in a closed circuit including coils 12, 14 and conduits 18, 20. System 10 also includes a thermal expansion valve 22 for heating with internal bypass, and a thermal expansion valve 24 for cooling with internal bypass.

A reversing valve 25 that reverses the flow of refrigerant through the circuit depending on whether system 10 is operating in a heating mode or a cooling mode. With a counterclockwise circulation, as indicated by arrows 16, system 10 operates in a heating mode (i.e., heats the indoor side of the circuit). Conversely, with a clockwise circulation, system 10 operates in a cooling mode. System 10 further includes a filter drier 26 and an accumulator 28.

According to the invention, a solar heat exchanger 30 is in contact with, and may encircle or surround conduit 20. Both exchanger 30 and conduit 20 may be formed of a thermally conductive material, such as copper, for example. Exchanger 30 may be donut-shaped or circular in cross section and substantially hollow. Exchanger 30 may have a fluid input 32 and a fluid output 34. Both input 32 and output 34 may be in fluid communication with solar heater 36. Solar heater 36 may heat water, propylene glycol, or some other heat transfer fluid and pump the water in the direction indicated by arrow 38 into exchanger 30.

While in exchanger 30, the heat in the water from heater 36 may be transferred to the saturated refrigerant in conduit 20. Such heat transfer may assist in heating indoor coil 12 and improve the efficiency of system 10. After passing through heat exchanger 30, the water exits through outlet 34 and returns to heater 36 where the water is re-heated and the cycle repeats.

According to the invention, when the water from heater 36 is hot enough, the heating operation of the air-to-air heat pump may be locked out such that all the heat produced by the system is produced exclusively by solar heater 36. Conversely, when system 10 operates in the cooling mode, solar heater 36 may be locked out such that the refrigerant is not heated further when passing through exchanger 30.

FIG. 2 a illustrates exchanger 30 including input 32 and output 34. FIG. 2 b further illustrates a sectional view of a central portion of exchanger 30. As shown, conduit 20 extends through exchanger 30. As also shown, the direction of refrigerant flow in conduit 20 may be opposite to the direction of water flow in exchanger 30. Heat exchanger 30 may be generally located between outside coil 14 and a liquid receiver including filter drier 26 and accumulator 28.

In one embodiment, heat exchanger 30 has a length 40 (FIG. 2 a) of approximately between twelve and fifteen inches. However, there may be no limit to the length of exchanger 30, and it may be up to about three feet long. Advantageously, the greater the length 40 of exchanger 30, the more completely it may transfer its heat to conduit 20.

In one embodiment, an inner cylindrical wall 42 of exchanger 30 is concentric with an outer cylindrical wall 44 of exchanger 30. Thus, exchanger 30 may have a donut-shaped cross section. However, in another embodiment, exchanger 30 has no inner wall 42 (or inner wall 42 may be thought of as being at least a part of conduit 20), and its opposite ends 46 are sealed fluid-tight against the outer surface of conduit 20. Thus, the heat transfer fluid with exchanger 30 directly contacts the outer surface of conduit 20. Thus, exchanger 30 may have a circular cross section. In both of these embodiments, the only path by which the heat transfer fluid may exit exchanger 30 may be through output 34.

FIG. 3 illustrates another embodiment of an air-to-air heat pump system 300 of the present invention. Heat from the solar water is used to heat the air coil first to get as much heat as possible in the conditioned air stream. The cooler water is then used to put heat in the heat pump refrigerant. System 300 includes a solar collector 302, such as a solar panel, that heats water, propylene glycol, or some other liquid and send the heated liquid in conduit 304 to a solar heat storage tank 306. After the heat in the liquid has been transferred to tank 306, a conduit 308 carries the liquid back to collector 302 for re-heating. A pump (not shown) may be used between solar collector 302 and tank 306 to create the circulation of liquid. In one embodiment, tank 306 may be as described in patent application Ser. No. 12/536,409, entitled Heat Storage and Transfer System, filed Aug. 5, 2009, which is hereby incorporated by reference in its entirety.

Within tank 306, the heat from collector 302 may be transferred to another liquid such as water or propylene glycol that circulates between tank 306, heat exchanger 310, and water coil 312. Conduit 314 carries hot liquid to heat exchanger 310 and water coil 312. The heat in the liquid is transferred to heat exchanger 310 and water coil 312, and is returned to tank 306 for re-heating via conduit 316.

Heat exchanger 310 may be incorporated in an air-to-air heat pump 318 such that heat exchanger 310 assists in the heating of the heat pump's refrigerant, such as described above with regard to FIG. 1. Heat pump 318 may be substantially similar to the heat pump described with regard to FIG. 1. Thus, the warm solar water may deliver heat to heat pump 318 so heat pump 318 can deliver full capacity heat when the ambient temperature is low.

FIG. 4 illustrates one embodiment of a forced air heat system 400 of the present invention that marries solar hot water heat to a forced air system. System 400 includes a solar collector 402, such as a solar panel, that heats water, propylene glycol, or some other liquid and send the heated liquid in conduit 404 to a solar heat storage tank 406. After the heat in the liquid has been transferred to tank 406, a conduit 408 carries the liquid back to collector 402 for re-heating. Conduits 404, 408 may be fluidly connected within tank 406 such that conduits 404, 408 conjunctively form a single, unitary conduit or coil within tank 406. A pump (not shown) may be used between solar collector 402 and tank 406 to create the circulation of liquid. In one embodiment, tank 406 may be as described in patent application Ser. No. 12/536,409, entitled Heat Storage and Transfer System, filed Aug. 5, 2009, which is hereby incorporated by reference in its entirety.

A valve controller 410 may control valves 412, 414 which may divert the heated liquid from solar collector 402 to a heat dissipater 416 where the heat may be used immediately for heating water or air, for example. To the extent that the need for immediate heat is satisfied, heat may alternatively diverted by controller 410 to storage tank 406.

Within tank 406, the heat from collector 402 may be transferred to another liquid such as water that circulates between tank 406, water heater 418, and hot water coil 420. Conduit 422 carries hot liquid to water heater 418 and hot water coil 420. The water in water heater 418 may be further heated in water heater 418 and released for use via conduit 426. The water expelled through conduit 426 may be replenished via a cold water supply conduit 428.

The heat in the water in conduit 422 may be transferred to hot water air coil 420 where the heat may be transferred to air in a return air duct of a forced air system. After passing through hot water coil 420, the water is returned to tank 406 for re-heating via conduit 424. Conduit 424 also receives cold water from the cold water supply via conduit 428.

A check valve 430 and a shutoff valve 432 may be provided between conduit 422 and the cold water inlet of water heater 418. A bypass shut off valve 434 may be provided between conduit 428 and the cold water inlet of water heater 418. Thus, the cold water inlet of water heater 418 may be selectively in fluid communication with conduit 422 and/or with cold water source 428.

A shutoff valve 436 and a check valve 438 may be provided between conduit 428 and cold water inlet 424 of storage tank 406. A circulation pump 440 and a zone valve 442 may be provided between conduit 422 and the hot water inlet of hot water coil 420. Pump 440 may circulate water between hot water coil 420 and conduit 422.

As described above, the cold water inlet of the water heater may be selectively in fluid communication with a source of cold water 428, and the conduit 424 may be selectively in fluid communication with the source of cold water 428. Conduits 422 and 424 may be in fluid communication with each other within tank 406, and thus may be referred to herein as being a single, unitary conduit. This unitary conduit conjunctively formed by conduits 422, 424 may be in the form of a coil within tank 406. In one embodiment, this coil is disposed radially outwardly from the coil formed by conduits 404, 408. Hot water coil 420 of the forced air heating system may be in selective fluid communication with the conduit that is conjunctively formed by conduits 422 and 424.

Temperature switches 444, 446 may control the egress of hot water from tank 406 via conduit 422 and the ingress of cold water into tank 406 via conduit 424, respectively. Switches 444, 446 may be disposed underneath a layer of insulation on the outside of tank 406.

While the present invention has been described with reference to specific exemplary embodiments, it will be evident that various modifications and changes may be made to these embodiments without departing from the broader spirit and scope of the invention as set forth in the claims. Accordingly, the specification and drawings are to be regarded in an illustrative rather than a restrictive sense. 

1. A heating arrangement comprising: a heat pump including: an indoor coil having an inlet and an outlet; an outdoor coil having an inlet and an outlet; a first conduit fluidly interconnecting the outlet of the indoor coil and the inlet of the outdoor coil; a second conduit fluidly interconnecting the outlet of the outdoor coil and the inlet of the indoor coil; a solar collector including a fluid inlet and a fluid outlet, the collector being configured to collect solar heat, transfer the heat to a heat transfer fluid, and pump the heat transfer fluid through the fluid outlet; and a heat exchanger in thermal engagement with the second conduit, the heat exchanger in fluid communication with the fluid inlet and the fluid outlet of the solar collector such that the heat transfer fluid circulates between the solar collector and the heat exchanger.
 2. An arrangement as in claim 1 in which said heat exchanger includes a chamber in fluid communication with the fluid inlet and the fluid outlet of the solar collector.
 3. An arrangement as in claim 1 in which said heat transfer fluid is propylene glycol.
 4. An arrangement as in claim 1 in which said heat exchanger is substantially cylindrically-shaped.
 5. An arrangement as in claim 4 in which said heat exchanger has a substantially donut-shaped cross section when viewed in a longitudinal direction of the heat exchanger.
 6. An arrangement as in claim 4 in which said heat exchanger has a substantially circular cross section when viewed in a longitudinal direction of the heat exchanger.
 7. An arrangement as in claim 1 in which said heat exchanger substantially surrounds the second conduit.
 8. A heating arrangement comprising: a heat pump including: an indoor coil having an inlet and an outlet; an outdoor coil having an inlet and an outlet; a first conduit fluidly interconnecting the outlet of the indoor coil and the inlet of the outdoor coil; a second conduit fluidly interconnecting the outlet of the outdoor coil and the inlet of the indoor coil; a solar collector including a fluid inlet and a fluid outlet, the collector being configured to collect solar heat and transfer the heat to a heat transfer fluid; and a heat exchanger substantially surrounding at least a portion of the second conduit, the heat exchanger being in fluid communication with the fluid inlet and the fluid outlet of the solar collector such that the heat transfer fluid may circulate between the solar collector and the heat exchanger and thereby transfer the heat to the second conduit.
 9. An arrangement as in claim 8 in which said heat exchanger includes a chamber in fluid communication with the fluid inlet and the fluid outlet of the solar collector.
 10. An arrangement as in claim 8 in which said heat transfer fluid is propylene glycol.
 11. An arrangement as in claim 8 in which said heat exchanger is substantially cylindrically-shaped.
 12. An arrangement as in claim 11 in which said heat exchanger has a substantially donut-shaped cross section when viewed in a longitudinal direction of the heat exchanger.
 13. An arrangement as in claim 11 in which said heat exchanger has a substantially circular cross section when viewed in a longitudinal direction of the heat exchanger.
 14. A heat storage and transfer apparatus comprising: a substantially hollow, substantially enclosed tank, the tank including first and second fluid inlets and first and second fluid outlets; a first conduit centrally disposed within the tank and being in fluid communication with the first inlet and the first outlet of the tank; a solar energy collection unit disposed outside the tank and being in fluid communication with the first inlet and the first outlet of the tank; a pump in fluid communication with at least one of the first conduit and the solar energy collection unit, the pump being configured to circulate a heat transfer liquid between the first conduit and the solar energy collection unit; a second conduit disposed within the tank and in fluid communication with the second inlet and the second outlet of the tank; a thermally conductive heat transfer medium substantially filling the tank and configured to receive heat from the first conduit, store the heat, and transmit the heat to the second conduit; and a water heater having a cold water inlet selectively in fluid communication with the second conduit.
 15. An apparatus as in claim 14 in which the cold water inlet of the water heater is selectively in fluid communication with a source of cold water.
 16. An apparatus as in claim 15 in which the second conduit is selectively in fluid communication with the source of cold water.
 17. An apparatus as in claim 14 further comprising a hot water coil of a forced air heating system, the hot water coil being in selective fluid communication with the second conduit.
 18. An apparatus as in claim 17 wherein the hot water coil is disposed in a return air duct of the forced air heating system.
 19. An apparatus as in claim 17 further comprising a pump configured to circulate water between the hot water coil and the second conduit.
 20. An apparatus as in claim 14 in which the second conduit is disposed radially outwardly from the first conduit. 